The technology of the present disclosure relates to an optical scanning device, an image forming apparatus including the optical scanning device, and a position adjustment method of a synchronization detection sensor mounted in the optical scanning device.
Conventionally, there has been known an optical scanning device mounted in an electrophotographic image forming apparatus. The optical scanning device is configured to emit light corresponding to image data at a predetermined write timing, thereby exposing a photosensitive drum. The optical scanning device has a light source, a deflector that deflects light emitted from the light source and converts the light into scanning light, an image forming lens that forms an image of the scanning light from the deflector on the photosensitive drum, and a synchronization detection sensor that detects a part of the scanning light as a write timing reference signal of the aforementioned image data. In this type of optical scanning device, there is a case in which an incident position of the scanning light for the synchronization detection sensor is deviated in a sub-scanning direction with respect to a design position due to thermal deformation at the time of an operation of the deflector or assembling errors of a reflective mirror. As a consequence, there occurs a problem that it is not possible to detect the scanning light by the synchronization detection sensor, and the like.
In order to prevent this problem, there has been proposed to perform position adjustment of the synchronization detection sensor such that the scanning light is incident into a center position of a light receiving surface of the synchronization detection sensor in the sub-scanning direction. In this adjustment method, a slit plate having a slit hole extending in the sub-scanning direction is used. At a center part of the slit hole in the sub-scanning direction, a width wide part enlarged in a main scanning direction is formed. The slip plate has been assembled and fixed to a front side of the synchronization detection sensor. The assembling is performed such that a center position (a position of the width wide part) of the slit hole, which has been formed in the slit plate, in the sub-scanning direction coincides with a center position of the synchronization detection sensor in the sub-scanning direction. In the position adjustment of the synchronization detection sensor, the synchronization detection sensor is moved vertically together with the aforementioned slit plate while sensing an output signal from the synchronization detection sensor by using a measuring equipment such as an oscilloscope. Then, in a position in which an output time of the output signal from the synchronization detection sensor is longest, the synchronization detection sensor is fixed by screws and the like.